Carbon fiber is a good material that has low expansion coefficient, high thermal conductivity, and well stability. Carbon fiber has the characteristic of carbon material and the softness of fiber, and therefore carbon fiber is widely used in various applications such as aircrafts, medicines, architectural structures, and etc. In general, polyacrylonitrile (PAN) carbon fiber is the most commonly used carbon fiber.
Formation of PAN requires oxidation and carbonization processes. During the oxidation process, an acid or base is added to the reaction as a catalyst, such that the oxidation reaction time and reaction temperature can be decreased. That is, the energy consumption and defects in the carbon fiber can be decreased by use of the catalyst. Conventionally, acidic monomer, such as itaconic acid, is copolymerized with PAN material as a catalyst. In other examples, a catalyst, such as a strong acid or a strong base, is added into PAN as an additive such that the oxidation reaction time and reaction temperature can be decreased. However, disadvantages of these catalysts include low boiling point, low thermal resistance, and poor compatibility with PAN. Furthermore, the chemical structure of these catalysts are very different from the oxidized fiber/carbonized fiber, and therefore, when PAN carbon fiber material is formed, these catalysts may become impurities of the carbon fiber and the physical property of the carbon fiber may be negatively affected.
Research has disclosed formation of a composite raw material including PAN and nanotube or graphene. Then, carbon fiber material made of carbon nanotube (CNT)/PAN is formed. In addition, certain research also discloses a composite raw material including PAN and pitch, and the carbon fiber of pitch/PAN is then formed. Advantages of the above described nanotube, graphene, or pitch include high thermal resistance, and therefore tenacity and modulus of the resulting carbon fiber can increase. However, these additives do not have a strong acidic or basic functional group that can serve as a catalyst. Therefore, it is desirable to provide a novel additive having a high boiling point, a high thermal resistance, good compatibility with PAN and a capability to serve as a catalyst.